Chemicals vs Kydex?

Specififally, would spray paint damage Kydex? I want to try a tiger-stripe pattern on a black Kydex sheath.
Apr 30, 2001
Here is a listing of all the testing done by GE on Kydex. All chemicals were tested by 7 days of Immersion at 73degF

50% Hydrofluoric Acid= No Change
30% Hydrofluoric Acid= No Change
62% Perchloric Acid= No Change
50% Perchloric Acid= No Change
30% Perchloric Acid= No Change
10% Hydrocloric Acid= No Change
30% Sulfuric Acid= No Clange
3% Sulfuric Acid= No Change
70% Nitric Acid= No Change
50% Nitric Acid= No Change
30% Nitric Acid= No Change
10% Nitric Acid= No Change
5% Acetic Acid= No Change
10% Citric Acid= No Change
100% Oleic Acid= No Change
10% Sodium Hydroxide= No Change
1% Sodium Hydroxide= No Change
10% Ammonium Hydroxide= No Change
2% Sodium Carbonate= No Change
5% Phenol= Slightly Whitened
10% Sodium Cloride= No Change
3% Hydrogin Peroxide= No Change
95% Ethyl Alcohol= No Change
50% Ethyl Alcohol= No Change
Acetone= Attacked
Ethyl Acetate= Attacked
Ethylene Dicloride= Attacked
Carbon Tetrachloride= Slightly whitened
Toluene= Attacked
Heptane= No Change
Trichloroethylene= Attacked
Lube oil= No Change
ASTM Oil #3= No Change
JP-4= No Change
JP-5= No Change
Water= No Change

Now you can see whey this stuff is so tuff. But wishing to paint it, you will have problems. The paint won't last and will chip off in a heart beat.

I learned a trick to fix this from a friend of mine who is an effects artist for Hollywood (Aliens 4, Godzilla, Mission to Mars ect.). You need to mix your paint with MEK, and then use an airbrush to apply it. The MEK will slighty desolve the very top surface of the Kydex and allow the paint to bond. You will then get many years of service out of your Tiger Striped sheath. Or better still, just have the guys at Blade Tech make a sheath for your out of their camo Concealex.


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[This message has been edited by R.W.Clark (edited 06-22-2001).]
R.W.- Thanks for all the info, very helpful! I figured that the Kydex would outlast the paint. I had planned on trying it, and buying a new sheath anyway if it didn't work.
<font face="Verdana, Arial" size="2">Originally posted by R.W.Clark:
You need to mix your paint with MEK, and then use an airbrush to apply it. The MEK will slighty desolve the very top surface of the Kydex and allow the paint to bond </font>

Please excuse the newbie questions. Is MEK = methyl-ethyl-ketone? (sp?) Where does one buy MEK? Could you use masking tape (or other tape) to create sharp edges on the paint job or would the MEK dissolve the tape adhesive and make a mess? If you can't use tape, is there another way to mask or block off the paint?

RokJok, you are correct about MEK. You should be able to find it in any well stocked paint center. I have seen it at Lowes, Home Depot, ect. Any paint store will have it.

As to the masking, that is a good question. I would say off hand that you should be OK using Laquer Masking Tape (the green stuff). There should not be so much MEK as to desolve the tapes adhesive. It is just to act as a bonding agent. I'll have to ask Caius about the exact mixture ratio. And just how they mask it off. But it should be fine. You can also try it out on some cheap PVC material before you use it on Kydex.

Another option would be just to use the camo tape you can get at any gun/hunting shop.


Proud Member : California Knifemakers Association
Be very careful using MEK. It attacks most plastics. It will instantly ruin most countertops, and many floor coverings. It will damage most painted surfaces.

As you can see from this list, Kydex is pretty resistant stuff. A few items do stand out on this list as hazards to Kydex that you might encounter in everyday life.

The household name for Acetone is nail polish remover. So, keep that away from your kydex products.

Toluene is sold at building supply/home stores. It's another strong solvent especially good for tape and label residues and as a degreaser.

Carbon Tetrachloride hasn't been sold to consumers for many years (it's been found to cause cancer and birth defects). But, it was a popular cleaning solvent (often sold as "Typewriter Cleaner") for many years and you might still have some of it around.

Trichloroethylene is another that has not been sold to consumers for many years (concerns about ozone depletion). But, I've still got a big bottle of it (don't tell anyone). It was commonly sold as an electronics cleaner and was also the key ingredient until a few years ago in the popular gun cleaner "Gun Scrubber". (The new formulation for Gun Scrubber, BTW, contains even more agressive solvents and you really need to be careful with it.)

As I recall, people have previously posted that DEET, the active ingredient in many insect repellents, attacks Kydex. This wouldn't surprise me as DEET attacks many plastics. (Really makes you want to spray this stuff all over your body, doesn't it?)

Xylene is not on this list. It's sold in building supply/home stores, even grocery stores under the name "Goof Off" (others too), and will attack many plastics. It's a great solvent for label and tape scum on blades, though.

Gasoline is not on this list. It does attack some plastics. One might suggest that it is save since oils and jet fuel don't attack Kydex. But, gas is a much different product and it often contains other additives. Maybe someone has some experience with gas on kydex.

Balisongs -- because it don't mean a thing if it ain't got that swing!
Also, my wife was a medical researcher for UCI and says that Toluene is a cancer causing agent. Nobody has been successfull at banning it yet. But she says to use a mask and a good thick pair of gloves. It can be absorbed through the skin just like MEK.


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